I used a LT4 Valve sping on my head and a 304 camshaft with 533/544 lift with a 1.6 rocker..

Looking back i think i was pretty stuiped for not changing them while i had the motor apart. But with a extra .20 lift will that really cause me problems? The camshaft shouldn't spin but to MAYBE 5900 or 6000.

I'm looking for a way to tell if they are not right for my application. I heard one guy say use a 1/16th feeler guage between the coils with the valve all the way open.. Any ideas on this?

 

Measuring is always good! One way to do it is to check the installed height, which is measured from the bottom of the valve spring retainer to the spring pocket in the cylinder head with the valve is closed. Then subtract the installed height from the coil bind height (which you can measure if you don't have the specs). The difference should be 0.060" plus the valve lift.

But in general, the LT4 springs are good to 0.525" and no more, depending on the installed height. And given their relatively low rate, I would not install them higher to get the necessary clearance.

Rich Krause

 

man, So .060 is the clearance you want at max lift?

I knew i should have swap those springs.. I had only a week to rebuild my motor and thats the only corner i cut.

 

one more thing, How do you check bind hieght? just by compressing the spring all the way to the head?

 

Right. The 0.060" is total clearance, not between each coil.

Valve lift+0.060" should be greater than or equal to installed height-coil bind height.

Rich Krause

 

My LT4 springs float at 5300 rpm with the lil' hotcam. As far as I'm concerned, they aren't any better than stockers. Since they cam with the car and I don't feel like yankin' them I just keep the revs down but thats the last spring I'd put in anything but a stock cam'd car.